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Pipercross airfilter Do you change the velocity stacks?
Northpole - 11/11/14 at 05:52 PM

I am going for a flat Pipercross foam filter (40 mm hight), but the velocity stacks are very close to the filter. What do you do?
I was told by the seller of Pipercross, to cut off the stacks, but is that a good idea?
Maybe the best solution is to get a Domed filter? That could be a problem as the bonnet is very close to the airfilter.

Any good ideas?

MikeRJ - 11/11/14 at 06:44 PM

How close are they? You can get surprisingly close to the end of a velocity stack without significantly affecting airflow; a rule of thumb is an absolute minimum of 1/4 of the diameter of the velocity stack. This gives the same "curtain area" as the area of the stack.

However, this is only if the foam is supported by something e.g. a mesh or plastic frame. Obviously if the foam is free to get sucked onto the velocity stack it will become very restrictive.

[Edited on 11/11/14 by MikeRJ]

r1_pete - 11/11/14 at 07:29 PM

I made a recessed backplate to get the clearance equal to the stack diameter.

ITB Progress 6
ITB Progress 6

danny keenan - 11/11/14 at 08:01 PM

Hi

We use 100mm Pipercross air filter on our hayabusa cars.don't cut them down,I did this on my first ever race car and was 9bhp down.
Please go on our Facebook page MK Sportscars.we have built 100s of hayabusa powered cars so have a look on there for tips

Thanks Danny

snapper - 12/11/14 at 05:43 AM



You could buy or build some stubby stacks

Northpole - 12/11/14 at 10:30 AM

quote:
Originally posted by MikeRJ
How close are they? You can get surprisingly close to the end of a velocity stack without significantly affecting airflow; a rule of thumb is an absolute minimum of 1/4 of the diameter of the velocity stack. This gives the same "curtain area" as the area of the stack.

However, this is only if the foam is supported by something e.g. a mesh or plastic frame. Obviously if the foam is free to get sucked onto the velocity stack it will become very restrictive.

[Edited on 11/11/14 by MikeRJ]


Thanks Mike.
The Pipercross filter foam I bought is only 40 mm high, because of the little space to the bonnet. When mounting, I noticed that the clearance between the stacks (I am now using all 4 as low stacks) and the filter foam, is appr. 3-5 mm! And this filter has mesh just for the 2 stacks in the middle, not for the 2 others. This is not good, as the foam would most likely been sucked in to the engine ;(
Maybe I could just add some mesh grid for the 2 stacks and go for it, but I really do not know if that is a good idea?
I am trying to replace this filter with a domed 65 mm high filter at the seller, but I have not heard from him yet....he told me this would be fine if I added 2 lower stacks, so all 4 would be low.

Northpole - 12/11/14 at 10:35 AM

quote:
Originally posted by danny keenan
Hi

We use 100mm Pipercross air filter on our hayabusa cars.don't cut them down,I did this on my first ever race car and was 9bhp down.
Please go on our Facebook page MK Sportscars.we have built 100s of hayabusa powered cars so have a look on there for tips

Thanks Danny


Thanks Danny.
This was very useful, as I was thinking of cutting them down. I could not find any info on the web on this.
I have liked your facebook.
Do you think 65 mm is okay with the lower stacks? And should the filter be with some kind of a grid(mesh) for all 4 stacks?
Any good advice's appriciated